2 Welding TechniquesManual Welding : The entire welding operation is performed by hand.Semi automatic Welding : This is same as manual welding, but only the filler wire will be feed automatically.Automatic Welding :The equipment performs entire operation without adjustment of any controls
3 Welding ProcessShielded metal arc welding (SMAW): an arc welding process where electric arc is produced between electrode and the work. The shielding is done by the coating of electrode , where it produces the co2 to cover the weld.Gas tungsten arc welding (GTAW) : an arc welding process that uses an arc b/w non consumable tungsten electrode and work. The shielding is supplied by external gasSubmerged arc welding (SAW) : an arc welding process where electric arc is produced between electrode and the work. The welding arc is shielded by flux Granules.
4 Welding ProcessGas metal arc welding (GMAW): an arc welding process that uses an arc b/w electrode & work. The shielding is supplied by external gasFlux cored arc welding (FCAW): an arc welding process where electric arc is produced between electrode and the work. The shielding is by the Flux which is inside the electrode.
5 Welding DefinitionsUnder bead Crack : when hydrogen percentage is more in the weld metal it flows in the fusion area and crack is formed in this area . To over come this we use Basic electrodes (Low hydrogen Electrode )Heat affected zone (HAZ) : The portion at which the base metal has not melted ,but its mechanical properties has been changed.Shielding : To prevent the molten metal from atmosphere oxygen ,to stabilize the arc .Preheat : It helps in slow cooling rate of the molten metal thus it reduces the residual stress which leads to crack.Post weld heat treatment (PWHT): It removes residual stress left in the joint which may cause brittle fracture.
6 Welding DefinitionsDirect current Electrode positive (DCEP) :The arrangement of Direct current arc welding leads in which the electrode is positive pole and work piece is negative pole.Direct current Electrode Negative (DCEN) :The arrangement of Direct current arc welding leads in which the electrode is negative pole and work piece is positive pole.
8 Destructive TestingImpact Test : To test the toughness of the material .Tensile Test : To test tensile strength of the material .Bend Test : To test the ductility of the material.Hardness Test : To test the ductility of the material.Nick break Test : To test the complete fusion and penetration.
9 Non-Destructive Testing Visual Testing: This is done by using naked eyes , Magnifying glass.Radiography Testing: This is by using X-rays or Gamma rays.Ultrasonic Testing: This is done by using Ultrasonic waves.Dye penetrate Testing: This is done by using liquid penetrates.Magnetic particle Testing: This is done by using Magnetic waves.
10 Welding Test positions in pipes 1G Position2G Position5G Position6G Position